Forces and Motion
Forces are all around us! Gravity pulls things down, friction slows things down, and simple machines make work easier.
Gravity: What Goes Up Must Come Down
Gravity is an invisible force that pulls everything towards the centre of the Earth. It is the reason things fall down when you drop them!
Gravity pulls the ball DOWN
The ground
Gravity in everyday life:
- ● An apple falling from a tree 🍎
- ● Water flowing downhill 💧
- ● You sliding down a slide at the park 🚵
- ● Rain falling from clouds 🌧️
- ● Keeping your feet on the ground when you walk!
Friction: The Slowing Force
Friction is a force that happens when two surfaces rub against each other. Friction slows things down and can also create heat.
Rough Surfaces = More Friction
Carpet
Hard to slide on
Rubber shoes
Grip the ground well
Sandpaper
Very rough and grippy
Smooth Surfaces = Less Friction
Ice
Very slippery!
Polished floor
Easy to slide on
Wet surface
Less grip, more sliding
Speed: Fast and Slow
Speed tells us how fast or slow something is moving. A bigger force can make things move faster.
Speed Comparison
Simple Machines
Simple machines make work easier by changing the direction or amount of force needed. Here are two important ones:
Ramp (Inclined Plane)
A ramp makes it easier to move heavy things up. Instead of lifting straight up, you push along a slope. It takes less force!
Examples: wheelchair ramp, slide, road up a hill
Lever
A lever is a bar that rests on a point (called a fulcrum). Push one end down, and the other end lifts up with more force!
Examples: seesaw, bottle opener, wheelbarrow
💡 Think About It!
If you need to move a heavy box onto a table, would it be easier to lift it straight up or push it up a ramp? What makes you say that? Why?
🧪 Try It at Home!
Friction Ramp Experiment
You will need: a book (to make a ramp), a small toy car, and 3 different surfaces.
- Prop one end of the book up to make a ramp
- Let the toy car roll down on the bare book (smooth surface)
- Cover the ramp with a towel (rough surface) and try again
- Cover the ramp with sandpaper (very rough) and try again
- On which surface did the car travel the furthest? The shortest?
- Think: which surface had the most friction? The least?
Smooth surfaces have less friction, so the car rolls further!
Key Vocabulary
Gravity
A force that pulls things towards the Earth. It makes things fall down.
Friction
A force between two surfaces that slows things down. Rough surfaces create more friction.
Speed
How fast or slow something is moving.
Simple Machine
A tool that makes work easier, like a ramp or lever.
Knowledge Check
Choose the correct answer for each question. Click "Check Answer" to see if you are right!
Question 1
What force pulls an apple down from a tree?
Question 2
Which surface would have the MOST friction?
Question 3
A ramp is useful because it...
Question 4
A seesaw is an example of which simple machine?
Question 5
Why does a ball eventually stop rolling on grass?
Key Concepts Summary
- ●Gravity pulls everything towards the Earth. What goes up must come down!
- ●Friction is a force between surfaces that slows things down. Rough surfaces have more friction.
- ●Speed measures how fast or slow something moves. More force = more speed.
- ●Simple machines like ramps and levers make work easier by changing the force needed.
- ●Forces are everywhere in our daily lives — from dropping a ball to riding a bike.